Dynamic crushing behavior and energy absorption of hybrid auxetic metamaterial inspired by Islamic motif art

Auxetic honeycomb structures are promising metamaterials with outstanding mechanical properties,and can be potentially used in energy absorption applications.In this study,a novel modified re-entrant hybrid auxetic metamaterial inspired by Islamic motif art is designed by integrating four-pointed double re-entrant motifs with symmetric semi-hexagonal unit cells to achieve a high energy absorption capacity(EAC).Theoretical analyses and numerical simulations are performed to examine the dynamic crushing behavior of the four-pointed double re-entrant combined structure(FDRCS).The developed finite element models(FEMs)are validated by the experiments under quasi-static compression.The deformation mode and stress-strain curves are further studied under low,medium,and high crushing velocities.The theoretically predicted plateau stress of the FDRCS under different crushing velocities is consistent with the numerical simulation results.The crushing stress and the EAC of the FDRCS are influenced by the geometric parameters and crushing velocities.The FDRCS exhibits a negative Poisson's ratio(NPR),owing to the four-point re-entrant structure(RES).Moreover,the specific energy absorption(SEA)of these structures is higher than that of nonauxetic hexagonal and auxetic re-entrant structures,owing to the generation of more plastic hinges that dissipate more energy during dynamic crushing.

Advances in high-performance MEMS pressure sensors:design,fabrication,and packaging

Pressure sensors play a vital role in aerospace,automotive,medical,and consumer electronics.Although microelectromechanical system(MEMS)-based pressure sensors have been widely used for decades,new trends in pressure sensors,including higher sensitivity,higher accuracy,better multifunctionality,smaller chip size,and smaller package size,have recently emerged.The demand for performance upgradation has led to breakthroughs in sensor materials,design,fabrication,and packaging methods,which have emerged frequently in recent decades.This paper reviews common new trends in MEMS pressure sensors,including minute differential pressure sensors(MDPSs),resonant pressure sensors(RPSs),integrated pressure sensors,miniaturized pressure chips,and leadless pressure sensors.To realize an extremely sensitive MDPS with broad application potential,including in medical ventilators and fire residual pressure monitors,the“beam-membrane-island”sensor design exhibits the best performance of 66μV/V/kPa with a natural frequency of 11.3 kHz.In high-accuracy applications,silicon and quartz RPS are analyzed,and both materials show±0.01%FS accuracy with respect to varying temperature coefficient of frequency(TCF)control methods.To improve MEMS sensor integration,different integrated“pressure+x”sensor designs and fabrication methods are compared.In this realm,the intercoupling effect still requires further investigation.Typical fabrication methods for microsized pressure sensor chips are also reviewed.To date,the chip thickness size can be controlled to be<0.1 mm,which is advantageous for implant sensors.Furthermore,a leadless pressure sensor was analyzed,offering an extremely small package size and harsh environmental compatibility.This review is structured as follows.The background of pressure sensors is first presented.Then,an in-depth introduction to MEMS pressure sensors based on different application scenarios is provided.Additionally,their respective characteristics and significant advancements are analyzed and summarized.Finally,development trends of MEMS pressure sensors in different fields are analyzed.